The present invention relates to a polyamide resin composition for producing polyamide packaging material having excellent and uniform transparency and also being excellent in blocking resistance (sliding property).
It has been known that the polyamide packaging material is excellent in pinhole-free property, oil resistance and oxygen barrier property, but conventional polyamide packaging material is liable to cause blocking thereby impairing the workability upon packing or packaging. As the method of improving the blocking resistance of a polyamide packaging material, there has been known a method of modifying the surface structure of a packaging material (refer to Japanese Patent Publication No. 40-958 (1965)), a method of adding a fatty acid amide (refer to Japanese Patent Publication No. 33-9788 (1958)) or a method of modifying the surface property of a packaging material by adding fine powder of inorganic substance (refer to Japanese Patent Laid-Open No. 49-42752 (1974)). Among them, the method of adding fine powder of inorganic substance have been most preferred for the improvement of the blocking resistance. By the way, in the case of adding fine powder of inorganic substance, the improvement for the blocking resistance conflicts with the high transparency and, particularly, in the case of a polyamide packaging material, hazing tends to occur due to crystallization of the fine powder of inorganic substance upon cooling, thereby often causing loss of transparency.
In view of the above, the present inventors have made an earnest study for providing a polyamide resin composition suitable to the production of packaging material which is improved in the blocking resistance without impairing the transparency and, as a result, have found that the blocking resistance can be improved without impairing the transparency by preparing a packaging material such as in the form of films, sheets, blowmolding containers, etc., using a polyamide composition containing from 0.01 to 1 % by weight of fine silica to polyamide resin and from 1 to 99 % by weight of a silane coupling agent to the fine silica. The present invention has been accomplished based on this finding.